The present invention relates to bulk assaying systems. More particularly, the present invention relates to apparatus, methods, and systems for assaying materials to detect the types and amounts of radiation.
The threat of environmental contamination with radioactively contaminated materials is a growing problem worldwide. As increasing numbers of industries use radiation energy in the course of business, increasing amounts of materials become radioactive and must be handled differently than other industrial waste products which end up in landfills or other raw or reusable materials which are recycled. Government guidelines as set by the Nuclear Regulatory Commission (NRC) and other state and federal regulatory agencies establish maximum acceptable radiation levels for organizations that are licensed to posses solid radioactive materials, to regulate the level of radiation that is released into the environment. The predetermined maximum values for such radioactive guidelines are in terms of total radioactive levels within or on the surface of the solid waste materials per unit weight. If the radiation levels of the materials are above a predetermined maximum regulatory limit, the licensed industry possessing this material is not allowed to release the material for conventional disposal in an ordinary landfill or for reuse/recycling. The parameter measured in determining feasibility of release from licensed controls to landfill disposal is typically based on the overall radiation level emanating from the material per unit weight or per unit surface area.
Thus far, attempts to regulate the amount of radioactive material released into the environment have focused on allowing no detectable amount of radiation in materials to be discarded through conventional landfills or by recycling. Related apparatus, methods, and systems for detecting radioactivity in solid material have only focused on ascertaining whether the materials exceed a general detectable regulated limit of radiation.
The related art, therefore, deals with the overall radiation level in screening or scanning of material to determine if there is presence of radioactivity. As such, the related art is generally in the field of screening/scanning railroad cars and trucks to determine whether cargo carried thereon has any signs of radioactivity. For example, a railroad car carrying metal scraps such as steel scrap on a track may travel through a screening apparatus having detectors on adjacent sides of the track. The detectors only respond to an appropriate level of overall radioactivity. A yes/no response is produced and if the level of radiation is below a predetermined regulatory level (the xe2x80x9cnoxe2x80x9d signal), then the scrap load is considered safe and reused as scrap metal or otherwise released to a landfill. Conversely, if the level of radiation is above a predetermined level (the xe2x80x9cyesxe2x80x9d signal), even if the signal is produced by a single item in a carload of scrap metal, then the scrap load is considered not safe because it is too radioactive and cannot be released to landfills or reused as scrap metal. These materials must be treated through radioactive material disposal protocols.
However, recent scientific findings and trends show that determining the total level of radiation is not as critical to assessing potential radiation damage to the environment as determining the type of radionuclide producing the radiation and the magnitude and type of radiation produced by that particular radionuclide. In other words, the determination of the type and amount of a specific radionuclide can be much more important than the overall radiation contributed by all materials. In light of recent proposals in the regulatory field, such as ANSI/HPS N13.12-1999 (American National Standards Institute, Inc./Health Physics Society: Surface and Volume Radioactivity Standards for Clearance), to place limits on the release amounts of specific types of radionuclides, the systems in use in the related art will become obsolete. ANSI/HPS N13.12-1999 is a regulatory standard intended to provide guidance for protecting the public and the environment from radiation exposure.
None of the related art makes any attempt to ascertain whether the radiation is equally dispersed throughout a load; what radiation, if any, is caused by what types of radionuclides; and finally, the magnitude of the level of radiation from each radionuclide. Thus, there is a need to create apparatus, methods, and systems that are capable of identifying individual radionuclides potentially present in the solid waste materials and then determining the quantity of each radionuclide, for compliance with recently proposed changes in regulations governing release of residual quantities of radioactivity in solid waste materials to the environment.
Accordingly, the present invention is directed to an apparatus, methods, and disadvantages of the related art. The present invention is designed to detect individual types of radionuclides and whether the quantity of each radionuclide meets or exceeds a predetermined regulatory limit.
To achieve these and other advantages and in accordance with the purposes of the invention, as embodied and broadly described, the invention includes an apparatus for assaying material comprising a support for holding a device for containing material, a scanning detector proximate the support to detect an area of radioactive non-uniformity in the material, and an assay detector proximate the support to assay radiation emanating from the material.
In accordance with another embodiment of the invention, the invention includes a method for assaying material comprising providing a device for holding or containing material, detecting for an area of radioactive non-uniformity in the material with a scanning detector, and assaying any radiation emanating from the material with an assay detector.
In accordance with another embodiment of the invention, the invention includes a system for assaying material comprising a support for holding a device containing material, an assay station including a scanning detector proximate the support to detect an area of radioactive non-uniformity in the material, and an assay detector proximate the support to assay any radiation emanating from the material, The system also includes means for delivering the device to the assay station, and means for removing the device from the assay station.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the apparatus, methods, and systems particularly pointed out in the written description and claims hereof as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.